Heretofore, releasable connecting devices as applied to the marine, ocean research, and commercial fishing industries utilize locking and releasing methods such as sliding load supports, spring-loaded pins, pivoted latches, swivel locking arms, trip levers, and, as disclosed in U.S. Pat. No. 4,813,731 issued to Smith on Apr. 21, 1989, which is directed to a pelican hook, and in U.S. Pat. Nos. 3,934,933; 3,979,803; and 4,850,254. These and similar methods have addressed the functional locking and releasing means for light to moderate tensile loads. Unfortunately, when such methods are used with heavy tensile loads, the release mechanisms absorb an excessive amount of the tensile load, resulting in increased friction on the mechanisms that requires an inordinate amount of force by the user to unlatch or release the mechanism and also resulting in premature fatigue of the mechanisms, which compromises the safety and locking security.
In order to transfer a high-tensile load from the release mechanism to the connecting body of the device and still providing releasability and locking security, devices such as that taught by Smith provide compound release mechanisms to dissipate the tensile load. This results in complex and bulky devices not easily handled and costly to manufacture.
The increased concern regarding safety at sea has alerted users of leverage-type release devices, such as pelican hooks, to search for safer alternative release mechanisms. Pelican hooks are generally used in conditions where the tensile load upon them exceeds their intended capacity and the user is given to using a hammer to dislodge the release apparatus, which is located dangerously close to the hook retaining the connecting link.
Ocean research requires that loads, i.e., anchors, surveying or monitoring equipment, etc., be dropped into the ocean from a deck-mounted crane. As this activity often occurs during inclement weather, safety is of the greatest concern. A release mechanism is preferred that provides multi-directional releasability from a single point on the device. This enables a user to quickly and safely select different methods of releasing the load, depending on the sea conditions at the time. One method of release is by pulling on the release lanyard manually, and the other method is attaching the release lanyard to the crane boom and lowering the load with the crane's winch to thereby cause release of the load. The latter method is the safest because in the manual method rotation of the load prior to its release does not prevent the release lanyard from becoming wrapped around the device and either causing inadvertent release or failure to release when desired.
The device disclosed by the inventor in his U.S. Pat. No. 5,100,192, issued on Mar. 31, 1992, offers an improvement over non-toggle linkage release mechanisms, but it does not provide multi-directional releasability from a single point on the device.
During the course of releasing a load under tension, there is often a delay time between applying the tensile load to the release mechanism and the actual release of the load. This requires safety measures, such as providing means to securely lock the release device and thereby prevent inadvertent release of the load.
Thus, devices, such as the inventor's device disclosed in the foregoing patent and also disclosed in the inventory's U.S. Pat. No. 5,123,374, provide a releasing mechanism that secures the connecting member but does not provide a means to securely lock the device in that position to prevent inadvertent release of the load.
In the case of toggle linkage release mechanisms, the ability to release a load under tension with the least degree of effort requires that the body and the releasing portion of the device equally share the load to be released. Devices, such as those disclosed by the inventor in his previous patents, teach the tensile loads on the device acting off-center or on different planes so as to unnecessarily increase the tensile load to the movable portion of the device and, thus, cause additional wear to the releasing mechanism, additional shock to the releasing mechanism, and requiring additional effort to release the device. Finally, another desirable feature is a release mechanism that dampens shock without requiring the use of additional levers and springs, such as those disclosed in the inventor's prior patents.